Telescope

Description

"The eye-end of a telescope. The reader will recognize the micrometer previously described. L is a paraffin lamp fitting by a bayonet joint into a copper cover c. This effectually defends its glass chimney against accident, and protects the lamp from wind. The simple means by which this lamp is made to preserve its verticality in all positions of the telescope is evident from the figure. By this lamp alone the bright wire or bright field illumination is given at pleasure, and with any desired intensity, simply by movement of the small pin p." —The Encyclopedia Britannica, 1903